wip for db_migrations for core schema

sql/pgsql/migrations/60.sql

@@ -0,0 +1,18 @@
+begin;
+
+alter table ttrss_user_entries alter column feed_id drop not null;
+
+create table ttrss_archived_feeds (id integer not null primary key,
+	owner_uid integer not null references ttrss_users(id) on delete cascade,
+	title varchar(200) not null, 
+	feed_url text not null, 
+	site_url varchar(250) not null default '');	
+
+alter table ttrss_user_entries add column orig_feed_id integer;
+update ttrss_user_entries set orig_feed_id = NULL;
+
+alter table ttrss_user_entries add constraint "$4" FOREIGN KEY (orig_feed_id) REFERENCES ttrss_archived_feeds(id) ON DELETE SET NULL;
+
+update ttrss_version set schema_version = 60;
+
+commit;